A body deformation sensor having a telescopic arm is employed in accident research in automobiles in crash test dummies (anthropomorphic test devices or ATD). The body deformation sensor senses body deformations of the crash test dummy with a temporal resolution of 0.05 msec and less. Thus, in a crash test an automobile frontally collides with an obstacle with a specific velocity. At least one crash test dummy is placed in the automobile. In the frontal impact, the crash test dummy is temporarily subjected to a high acceleration and the body of the crash test dummy is deformed. Regionally, the crash test is regulated by the Euro New Car Assessment Program (Euro NCAP) or the US New Car Assessment Program (US NCAP), for example. According to these regulations, the body acceleration of the crash test dummy has to comply with certain limit values. Thus, according to Euro NCAP or US NCAP the limit value for chest acceleration of the crash test dummy is 60 g for a period of time of at least 3 msec.
The document US20050206910A1, which is herein incorporated herein by this reference for all purposes, discloses such a body deformation sensor having a telescopic arm that extends along a longitudinal axis from a first end to a second end. The telescopic arm is reversibly slidably collapsible along the longitudinal axis, thereby changing its length. A light source is arranged within the telescopic arm at the first end, while a light receiver is arranged at the second end. The light receiver detects a luminance of light emitted from the light source. The luminance detected varies with the length of the telescopic arm.
The body deformation sensor can be mounted in the chest of a crash test dummy. Thus, document US20050206910A1 shows how the telescopic arm is arranged with its longitudinal axis parallel to a horizontal axis of the crash test dummy. Upon deformation of the chest along its horizontal axis, the telescopic arm slidingly collapses, thereby changing its length. The light receiver detects the change in length as a change in luminance. The change in luminance is a clear output signal indicating deformation of the chest along the longitudinal axis.
It is an object of the present invention to improve a body deformation sensor having a telescopic arm.